linux-kernel - Re: [PATCH 3/5] clk: eyeq5: add controller

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Date: Tue, 02 Jan 2024 15:42:45 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Conor Dooley <conor+dt@...nel.org>, Gregory CLEMENT <gregory.clement@...tlin.com>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Michael Turquette <mturquette@...libre.com>, Rob Herring <robh+dt@...nel.org>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>, Théo Lebrun <theo.lebrun@...tlin.com>
Cc: Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, linux-mips@...r.kernel.org, linux-clk@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Tawfik Bayouk <tawfik.bayouk@...ileye.com>
Subject: Re: [PATCH 3/5] clk: eyeq5: add controller

Quoting Théo Lebrun (2023-12-22 03:25:12)
> On Wed Dec 20, 2023 at 12:09 AM CET, Stephen Boyd wrote:
> > Quoting Théo Lebrun (2023-12-18 09:14:18)
> 
> > > +       of_clk_add_hw_provider(np, of_clk_hw_onecell_get, data);
> > > +}
> > > +
> > > +CLK_OF_DECLARE_DRIVER(eq5c, "mobileye,eyeq5-clk", eq5c_init);
> >
> > Please use a platform driver.
> 
> I've been trying to do that but I had a stall at boot. I initially
> associated it with the UART driver acquiring a clock too early but
> instead it is the CPU timer clocksource driver that consumes one of our
> clock way earlier than any platform driver initialisation.
> 
> The clocksource driver we are talking about is this one for reference:
> https://elixir.bootlin.com/linux/v6.6.8/source/drivers/clocksource/mips-gic-timer.c
> 
> Its usage of TIMER_OF_DECLARE means it gets probed by timer_probe ->
> plat_time_init -> time_init -> start_kernel. This is way before any
> initcalls. Our prior use of CLK_OF_DECLARE_DRIVER meant that we got
> probed by of_clk_init -> plat_time_init.
> 
> I'm guessing we are not the first one in this situation; any advice on
> how to deal with it?
> 

You guessed correctly. In that case, use CLK_OF_DECLARE_DRIVER() and
register the clk(s) needed for the timer in that function. Other clks
shall be registered with a platform driver.